substr() function is used when you want to remove part of the string. It takes three parameters.
See the substr() structure
First one for mentioning the string,
Second one is for where to start to,
Third one is for how many strings to keep,
<?php echo substr("Hello world dbestech ",0, 6); ?>
The output is
The above function starts to count the string from the 0th character and keep 6 of them and remove rest of them.